WO2004096317A2

WO2004096317A2 - Flush catheter with flow directing sheath

Info

Publication number: WO2004096317A2
Application number: PCT/US2004/012809
Authority: WO
Inventors: Michael Atlas
Original assignee: Lightlab Imaging, Inc.
Priority date: 2003-04-25
Filing date: 2004-04-26
Publication date: 2004-11-11
Also published as: US20040215166A1; US7241286B2; US7625366B2; US20070260198A1; WO2004096317A3

Abstract

A flush catheter (10) is provided which is configured to be introduced into an orifice to create a flush zone therein. The flush catheter (10) includes a catheter body (11) having an inner cavity (14), the inner cavity being configured to communicate with a source of flush solution, one or more openings (15) configured to expel therethrough flush solution, and a sheath (45) at least partially covering the one or more openings, wherein when flush solution is expelled through the one or more openings, the flush solution is directed by the sheath to flow along an outer surface of the catheter body, (11) thereby creating a flush zone along a length of the outer surface of the catheter body. The flush catheter may be used in combination with an image catheter/probe (36) such as an image catheter/probe utilized in OCT imaging systems.

Description

FLUSH CATHETER WITH FLOW DIRECTING SHEATH

BACKGROUND OF THE INVENTION

1. Field of the Invention

[1] The invention is directe to a flush catheter and, more particularly, to a flush

catheter provided -with a flow directing sheath.

2. Background of the Related Art

[2] In order to obtain clear in-vivo images of arterial walls when using, for example,

Optical Coherence Tomography (OC ), it is necessary to displace blood from, a cylindrical

volume around a tip of an imaging probe. To allow surveying of a length of an artery wall, it is

desirable that the cylindrical volume be, for example, as long as approximately 40-50 mm or

more. The better the blood is cleared from this volume, the better the image obtained of the

arterial wall.

[3] For example, in almost all uses of OCT for imaging during cardiac catherizations,

an imaging probe disposed within a guide catheter is inserted into an artery such that a direction

of blood flow is from a proximal end of the imaging probe toward a distal end of the catheter or

probe. It is desirable that a location of the cleared cylindrical volume be somewhat proximal to

the distal end of the catheter, to allow the use of a "minirail" delivery system. A "minirail"

delivery system utilizes a guide wire and a flexible tip attachable to the imaging probe. The guide

wire is used to guide the imaging probe into the desired artery. [4] Previous and current methods of achieving the desired cleared volume or blood

displacement have included the use of cardiac dilation balloons, the injection of saline through a

guide catheter, and the injection of saline through a selective flush catheter inserted over the

imaging catheter. All three of these methods provide less than ideal solutions.

[5] The balloon method either involves total occlusion of a vessel for the time that

the image is desired, or the use of under-inflated balloons which does not completely remove the

blood from the field of view. The guide flush method requires a large flow rate of saline that

can over hydrate the patient. This method is also very ineffective when side branches are

present.

[6] For example, when blood flow is fro a proximal to a distal end of the imaging

probe, the selective flush catheter method has the inherent limitation that blood from the area

proximal to the flush point is entrained into the flush solution at a point where the flush solution

exits the catheter. Increasing the flow rate of flush solution tends to entrain more blood, making

it difficult to dilute the blood enough to provide a clear imaging area. In addition, it is difficult

to configure this type of device for a minirail delivery system.

[7] U.S. Patent No. 4,878,893 (hereinafter "the 893 patent") to AlbertK. Chin entitled

_ "Angioscope with Flush Solution Deflector Shield," which is hereby incorporated by reference,

provides a partial solution to this problem, and is intended for use with an angioscope catheter.

The 893 patent teaches the use of a curved deflector shield 30 bonded to a distal tip of a catheter

10. The deflector shield 30:

...causes the flushing solution to momentarily flow against blood flow toward the proximal end of the catheter. The blood flow will then carry the solution back past the distal tip of the angioscope 18, as shown in Fig. 13 [of the 893 patent] to provide the bolus required for clear visualization

as discussed at col. 5, lines 1-6, of the 893 patent. However, die approach of the '893 patent has

several deficiencies which prevent its use in an OCT application and which make it difficult to

produce.

[8] For example, the deflector shield must be at a distal end of the catheter, making it

difficult to use a minirail type of delivery system. Furdier, the design does not strongly direct the

flushing solution in an axial proximal direction. This results in much of the flushing solution

moving out from the catheter in a radial direction. As such, the bolus of flushing solution does

not flow very far toward the proximal end of the catheter and will not provide the long volume

desirable for surveying a length of the artery wall. Furthermore, radially directed jets of fluid can

damage the sensitive endothelial layer of the vessel and could even perforate the vessel.

[9] The above references are incorporated by reference herein where appropriate for

appropriate teachings of additional or alternative details, features and/ or technical background.

SUMMARY OF THE INVENTION

[10] An object of the invention is to solve at least the above problems and/or

disadvantages and to provide at least the advantages described hereinafter.

[11] The invention is; directed to a flush catheter, and more particularly, to a flush

catheter with a flow directing sheath. [12] Additional advantages, objects, and features of the invention will be set forth in

part in the description which follows and in part will become apparent to those having ordinary

skill in the art upon examination of the following or may be learned firom practice of the

invention. The objects and advantages of the invention may be realized and attained as

particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[13] The invention will be described in detail with reference to the following drawings

in which like reference numerals-refer to like -element^'s^' wherein:^"

[14] Figure 1 is ^'a schematic, partial, side, perspective view of a ^'flush catheter

implemented in combination with an imaging probe .according to an embodiment of .the

invention;

[15] Figure 2 is a schematic, partial, side, cross-sectional view of the flush catheter

implemented in combination with an imaging probe of Figure 1;

[16] Figure 3 is another schematic, partial, side, perspective view of the flush catheter

implemented in combination with an imaging probe of Figure 1;

[17] Figure 4 is another schematic, partial, side, cross-sectional perspective view of the

flush catheter implemented in combination with an imaging probe of Figure 1;

[18] Figure 5 is a schematic, partial,, side.view_^of, the. flush catheter _:implem.entedin._J

combination with an imaging probe of Figure 1; [19] Figure 6 is a schematic, partial, side, cross-sectional view of the flush catheter

implemented in combination with an imaging probe of Figure 1; and

.[20] Figure 7 is an enlarged, schematic, side, cross-sectional view of the sheath

according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[21] The invention is directed to a flush catheter configured to be inserted into an

artery, vessel, or other orifice in a patient The flush catheter includes a catheter body, having a

hollow inner cavity. The inner cavity is configured to communicate with a source of flush

solution. The flush solution used may be, for example, sterile physiological saline, pure contrast,

solution, or a mixture of sterile saline and angiographic contrast solution. Other fluids may also

be appropriate based on the particular application. One or more openings may be formed in an

outer surface of the catheter body and may be arranged radially around a periphery of the

catheter body in one or more rows.

[22] The flush catheter further includes a sheath. According to one embodiment of

the invention, the sheath can be formed of a thin piece of material of slightly larger inner

diameter than an outer diameter of the catheter body. The sheath is positioned over the one or

more openings and may be attached to the catheter body with ah attaching means. In one

embodiment the sheath is attached to, the cathetetrbpd -at :only one end thus creating-- n-

annular volume open at the other end and extending along a length of the catheter body. In one

embodiment, the sheath is attached to the catheter body at one end creating an annular volume open on an end facing a proximal end of die catheter when inserted into an artery, vessel, or

other orifice, and extending along a length of the catheter body.

[23] The flush catheter according to the invention may include a minirail delivery

system at a distal end. In the case of a minirail delivery system, d e one or more holes would be

positioned a distance proximal to where the minirail attaches to the flush catheter.

[24] For use with humans or animals, the sheath is preferably formed of a

biocompatible material. For OCT or other imaging applications, the sheath is preferably

transparent to allow light or other electromagnetic radiation to pass therethrough. In one

embodiment, the sheath is formed of transparent polyethylene terephthalate (PET), although

other materials may be appropriate based on the particular application.

[25] Upon operation, the flush catheter is introduced into an artery, vessel, or other

orifice of a patient. Flush solution provided by a flush solution source, in communication with

the inner cavity is directed through the inner cavity and radially outward through the one or

more openings. The flush solution is then directed axially along an outer surface of the catheter

body by die flow directing sheath.

[26] That is, die flush solution introduced into the catheter from the proximal end

flows radially out of the holes and is directed by the sheath along the outer surface of the flush

catheter in a proximal direction. As the flush solution interacts with the blood flowing from the

proximal end to the distal end of the flush catheter, it spreads out in the artery, vessel, or other „

bodily cavity or orifice, effectively substantially clearing a volume of the artery, vessel, or other

bodily cavity or orifice. [27] For example, in the case of a blood vessel, by using an appropriate amount of

flush solution an entire cylindrical volume may be substantially cleared of blood, using a flush

flow rate significandy less than the flow rate of blood in the vessel. The ability to substantially

clear a vessel of blood in an extended area while using a minimal rate of flush solution is one of

die advantages of the invention. .

[28] The size and location of the one or more openings relative to an open end of the

sheath may be chosen to allow for a substantially radially uniform flow of the flush solution

from the sheath. By varying an inner diameter of the sheath and/ or the catiieter, a thickness of

the annular gap may be modified, aHό wing for ^"an average axial velocity of the^' flush solution to

be controlled- for a given .flush flow rate. ■

[29] By doing this, the momentum of the flush solution (proportional to Average

Velocity x Mass Flow Rate of the flush solution) leaving the sheath may be varied to counteract

the momentum of the blood flowing in the vessel. By raising the average velocity of the flush

solution, a smaller mass flow rate can still counteract a larger but slower moving mass flow rate

of blood. By varying the gap between the sheath and flush catheter, the momentum of the flush

solution can be tuned to give the optimal length of cleared volume proximal to the sheadi for a

given application while using a minimal amount of flush solution.

[30] Because all of the flush solution leaves the flush catheter in an axial direction,

d ere is littie worry of producing damage to the arterial or vessel wall. In addition, the proximity

of the flush solution flow to the outer surface of the flush catheter substantially clears the outer

surface of blood. [31] A specific embodiment of a flush catheter according to d e invention will now be

discussed in detail below. The following discussion teaches using the flush catheter in

combination with an imaging catheter /probe, such as an image catheter/probe associated with

an OCT device. However, the invention can be applied to other applications for which

controlled flushing of an area is desirable.

i [32] Further, d e flush catheter of Figures 1-7 is shown used with a minirail delivery

system. However, other delivery systems may also be appropriate.

[33] Figure 1 is a schematic, partial, side, perspective view of a flush catheter

implemented in combination.. with an imaging probe according to -.an embodiment of the

invention. Figure 2 is a schematic, partial, side, cross-sectional view of die flush catheter

implemented in combination with an imaging probe of Figure 1. Figure 3 is another schematic,

partial,, side, perspective view of the flush catheter implemented in combination with an imaging

probe of Figure 1. Figure 4 is another schematic, partial, side, cross-sectional perspective view

of the flush catheter implemented in combination with an imaging probe of Figure 1. Figure 5 is

a schematic, partial, side view of , the .flush catheter implemented in combination with an imaging .

probe of Figure 1. Figure 6 is a schematic, partial, side, cross-sectional view of the flush catheter

implemented in combination with an imaging probe of Figure 1. Figure 7 is an enlarged,

schematic, side, cross-sectional view of the sheath according to the invention.

[34] Figure 1 shows a flush catheter assembly 1 comprising a flush catheter 10. In the

embodiment of Figure 1, the flush catheter 10 is shown used in combination with a minirail

delivery system 55. The minirail delivery system 55 includes a flexible tip 56 provided as part of d e flush catheter 10 or configured to attach to the flush catheter 10, removably or permanendy.

The flexible tip 56 is configured to receive a guide wire 20, as shown in Figure 1. The guide

wire 20 allows the flush catheter 10 to be guided into an artery, vessel or other bodily cavity or

orifice by a surgeon or other user.

[35] For OCT imaging use, it is preferable that the flush catheter be made of a material

that is transparent to the wavelengd s of light used. For use with humans or animals, it is

preferably that the flush catheter be made of a material that is biocompatible. One appropriate

material that is both transparent and biocompatible is clear thermoplastic, one example of which

is Polyester Block Amide, known as PEBA. However, other materials may also be^" appropriate. ^■

[36] The flush catheter 10 includes a catheter body 11 having an inner cavity 14. The

inner cavity 14 is configured to communicate with a source of flush solution (not shown). The

flush solution used may be, for example, sterile physiological saline, pure contrast solution, or a

mixture of sterile saline and angiographic contrast solution. Other fluids may also be

appropriate based on the particular application.

[37] The inner cavity 14 is configured to receive animaging core 35. The imaging core

35 includes an outer casing 37 in which an imaging probe 36, for example, a wire or optical fiber,

is disposed. The imaging probe 36 is designed to output a beam of light 30 radially. The beam

of light extends down a length of the imaging probe 36 and is deflected radially by a mirror 38.

The imaging probe 36 may be rotated witiiin the imaging core 35 to provide a disk-like scan of a

target, such as an inner wall of an artery, vessel, or other bodily cavity or orifice. The imaging

probe 36 may then be pulled lengthwise to scan a length of the target. That is, the imaging core 35 may be moved axially between a position underneath the flush sheath 45 proximal a distal

marker band 26 to die proximal marker band 25. In this way, a survey may be made of a length

of d e wall of the artery, vessel, or other bodily cavity or orifice.

[38] The imaging core 35 and imaging probe 36 are both preferably formed of a

transparent material to allow die light beam 30. top^'ass therethrough. For example, the imaging-

core may be formed of polyester block amide, known as PEBA, onylon and die imaging probe

may be formed of, for example, silica glass. However, other materials may also be appropriate.

[39] As mentioned above, the flush catheter 10. further includes distal and proximal

marker bands 25, 26, whichmaybe-raised-as in-the-emhodiment'σfFigure ""Th:e marker bands- ^'

25, 26 are configured to allow a user to control the position of the flush catheter 10 and/ or

imaging probe 36. For example, the marker bands may be configured to be visible on, for

example, an angiogram and may be used to find the position of the catheter in, for example, an

arterial system. Also, if the marker bands are opaque to the O.C.T. probe, they provide a

reference during pullbacks.

[40] The flush catheter further includes one or ore op enings.15, as. shown in. Figure

2, disposed in the catiαeter body 11. The one or more openings may be formed in an outer

surface 12 of d e catheter body 11 and may be arranged radially around a periphery of the

catheter body 10 in one or more rows 15A, 15B.

[41] Further, the flush cati eter 10 further includes a sheath 45. The sheath 45 at least

partially covers the one or more openings 15. The sheath 45 may comprise a thin piece of

material and may be in the form of a cylinder disposed around the outer surface 12 of the catheter body 11 and extending a predetermined distance D along die length of the catheter

body, as shown in Figure 7.

[42] The sheath 45 may be attached to an outer surface 12 of the flush catheter 10 by

an attaching means 40, such as an adhesive. In one embodiment, the sheath is attached to die

cadieter body 11 at one end creating an^r nnular volume open on an end facing a proximal end of

die cadieter 10 when inserted into an artery, vessel, or other bodily cavity or orifice. A gap G is

formed between d e inner surface 44 of d e sheath 45 and the outer surface 12 of the catheter

body 11.

[43] In operation, theιflush_sO.lutiΩ .frθK

through inner cavity 14 and is expelled through opening(s) 15, The flush solution expelled

through opening(s) 15 is directed by sheath 45 to flow along the outer surface 12 of the flush

cadieter 10, as shown by reference numeral 50 in Figures 2 and 7, forming a flush zone

extending from the opening(s) 15 along die outer surface 12 of the flush catheter 12 to at least

the distal marker band 25.

[44] By varying a distance of the gap G formed between the sheath 45 and- the.

opening(s) 15, the flow 50 can be controlled. That is, flush solution introduced into die flush

catheter 10 from the proximal end flows radially out of the opening(s) 15 and is directed by the

sheath 45 along the outer surface 12 of the flush catheter 10 in a proximal direction. The flush

solution leaves the sheath 45 moving axially in a proximal direction. As the flush solutio ^'

interacts with blood and/or other ^'matter coming from the proximal to the distal end it will begin

to spread out in the artery, vessel, or other bodily cavity or orifice, effectively substantially clearing a volume of the artery, vessel, or otiier bodily cavity or orifice of blood and/or other

matter. The distal and/ or proximal marker bands 25, 26 may be contoured to avoid blocking

die flow of the flush solution along the outer surface 12 of the flush catheter 10. In addition, the

distal and/or proximal marker bands 25, 26 may be sized to effectively prevent open edges 46A,

46B of die sheath 45 from contacting the^' walls^' of the -artery, vessel, or other bodily cavity or

orifice, minimizing d e chances of damage when moving the entire flush catheter in a proximal

direction.

[45] . By using an appropriate amount of flush solution, an entire cylindrical volume

between die two marker bands 25, 26 ma be substantially cleared of blood and/ or. otiier matter^'

creating a flush zone, using a flush flow rate significantly less than the flow rate of blood in the

artery, vessel, or other bodily cavity or orifice. The ability to substantially clear an artery, vessel,

or other bodily cavity or orifice of blood and/or otiier matter in an extended area while using a

minimal rate of flush solution is one of the advantages of the invention.

[46] The size and location of the opening(s) 15 relative to the open end 46 of the

sheath 45 may be chosen to allow for a substantially radially uniform flow of the flush solution

from the sheath 45. By varying an inner diameter of the sheath 45 and/ or the flush catheter 10,

a thickness of the annular gap G may be modified, allowing for an average axial velocity of the

flush solution to be controlled for a given flush flow rate. By doing this, the momentum of the

flush solution (proportional to Average Velocity x Mass Flow Rate of the flush solution) leaving

the sheath 45 may be varied to counteract the momentum of the blood and/or other matter

flowing in the artery, vessel, or other orifice. By raising the average velocity of the flush solution, a smaller mass flow rate can still counteract a larger but slower moving mass flow rate

of blood and/or otiier matter. By varying the gap G between the sheath 45 and flush catheter

10, die momentum of the flush solution can be tuned to give the optimal length of cleared

volume proximal to the sheath 45 for a given appKcation while using a minimal amount of flush solution. ^{" •} .- . . - ^■ . - . . . -^•

[47] Because all of the flush solution leaves the flush catheter 10 in an axial direction,

there is litde worry of producing damage to the walls of the artery, vessel, or other bodily cavity

or orifice. In addition, the proximity of the flush solution flow to the outer surface- 12 of the

catheter 10 substantially clears the outer surface 12^)f blood and/ or other matter, resulting in a

substantially clear image produced by the imaging probe 36.

[48] Although the details of the flush catheter according to the invention have been

optimized for its use in an OCT application, it is obvious that it may be easily modified for use

in other applications, in particular where a complete flush is desired while using a minimum

amount of flush solution.

[49] Further, the design allows the flush zone to be placed anywhere^' along the flush

catheter, merely by moving the positions of the opening(s) 15 and sheath 45. In applications

where the flush catheter is introduced in the opposite direction, i.e. blood flow is toward a distal

end of the flush catheter, the sheath may be reversed to provide effective flushing.

[50] Further, by varying the gap between the sheath and the flush cadieter, the average

velocity of the flush solution leaving axially from the sheath may be controlled for a given flush

rate. Additionally, by varying d e number, size, and location of the opening(s) relative to the open end of d e sheath, substantially non-uniform flows may be achieved for special

applications.

[51] The foregoing embodiments and advantages are merely exemplary and are not to

be construed as limiting the invention. The present teaching can be readily applied to other

types of apparatuses. The description of the invention is intended to be illustrative, and not to

limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to

those skilled in the art. In the claims, means-plus-function clauses are intended to cover the

structures described herein as performing the recited function and not only structural equivalents

but also equivalent structures.

Claims

WHAT IS CLAIMED IS:

1. A flush catheter configured to be introduced into an orifice to create a flush zone

therein, comprising:

^• a catheter body having an inner cavity, the inner cavity being configured to

communicate with a source of flush solution;

one or more openings configured to expel therethrough flush solution;

a sheath at least partially covering the one or more openings, wherein when flush

solution is expelled through the one or more openings, the flush solution is directed by the

sheath to flow along an outer surface of the catheter body, thereby creating the flushzone along

a length of the outer surface of the catheter .bod

2. The flush cadieter of claim 1, wherein a distance between the outer surface of the

catheter body and an inner surface of the sheath determines an average axial velocity of the flush

solution for a given flush solution flow rate.

3. The flush catheter of claim 1, wherein the sheath comprises a thin piece of

material in the form of a cylinder disposed around the catheter body, and wherein the sheath

extends a predetermined distance along a length of the catheter body.

4. The flush catheter of claim 3, wherein the sheath is attached to the catheter body

by an attaching means at one end thereo .

5. The flush cadieter of claim 4, wherein the attaching means is an adhesive.

6. The flush cadieter of claim 4, wherein a size, number, and location of the one or

more openings relative to an open end of the^'sheath are configured to create a substantially

uniform flow of flush solution, long the outer surface of the catheter body.

7. The flush catheter of claim 4, wherein a. size, number, and location of the one or

more openings relative to an open end of the sheath are configured to create a substantially non-

uniform flow of flush solution along d e outer surface of the catheter body.

8. The flush catheter of claim 1, wherein the sheath is formed of a biocompatible

material.

9. The flush catheter of claim 1, wherein the sheath is formed of a transparent

material.

10. The flush catheter of claim 1, wherein the sheath is formed of polyethylene

terephthalate.

11. The flush catheter of claim 1 , wherein a position of the one or more openings and

die sheath determine a position of the flush zone.

12. The flush catheter of claim 1, wherein the one or more openings are formedin the

outer surface of die catheter body.

13. The flush catheter of claim 12, wherein the one or more openings comprise a

plurality of openings arranged radially around the catheter body.

14. The flush catheter of claim 13, wherein the plurality of openings are arranged in

one or more rows arranged radially around the catheter body.

15. The flush catheter of claim 1 , wherein when the flush catheter is introduced into

an orifice it has a distal end and a proximal end, and the flush solution is directed by the sheath

to flow along the outer surface of the catheter body toward the proximal end of the flush

catheter, thereby creating the flush zone along the outer surface of the catheter body.

16. An imaging device configured to be introduced into an orifice to create a flush

zone therein, comprising:

an image probe; a flush catheter having a cadieter body with a hollow cavity configured to receive

therein the image probe and to communicate with a source of flush solution, and one or more

openings configured to expel therethrough flush solution;

a sheath at least partially covering d e one or more openings, wherein when flush

solution is expelled through the one or more openings, the flush solution is directed by d e

sheath to flow along an outer surface of the catheter body, thereby creating a flush zone along a

length of the outer surface of the catheter body.

17. The imaging device of claim 16, wherein a distance between the outer surface of.

the catheter and an inner surface of the sheath determines an average axial velocity of the flush

solution for a given flush solution flow rate.

18. The imaging device of claim 16, wherein the sheath comprises a thin piece of

extends a predetermined distance along a length of the catheter body.

19. The imaging device of claim 18, wherein the sheath is attached to the catheter

body by an attaching means at one end tiiereof.

20. The imaging device of claim 19, wherein the attaching means is an adhesive.

21. The imaging device of claim 19, wherein a size, number, and location of the one

or more openings relative to an open end of the sheath are configured to create a substantially

uniform flow of flush solution along the outer surface of the catheter body.

22. The imaging device of claim 19, wherein a size, number, and location of the one

non-uniform flow of flush solution along the outer surface of the catheter body.

23. The imaging device of claim 16, wherein the sheath is formed of a biocompatible-_.

material.

24. The imaging device of claim 16, wherein the sheath is formed of a transparent

material.

25. The imaging device of claim 20, wherein the sheath is formed of polyetiiylene-

terephthalate.

26. The imaging device of claim 16, wherein a position of the one or more openings

and the sheatii determine a position of the flush zone.

27. The imaging device of claim 16, wherein the one or more openings are formed in

the outer surface of die catheter body.

18. The imaging device of claim 26, wherein the one or more openings comprise a

plurality^' of openings arranged radially around the catiieter body.

29. The imaging device of claim 27, wherein d e plurality of openings are arranged in

one or more rows arranged radially around the catheter body.

30. The imaging device of claim 16, wherein when the flush catheter is introduced

into an orifice it has a distal end and a proximal end, and the flush solution is directed by the

sheath to flow along the outer surface of the catheter body toward-the proximal end of the flush